The present invention relates to a process and apparatus for providing in digital form information indicative of the outer contour of a leaf-like article and the holes that it may comprise, when these holes must be taken into consideration, in view of their dimensions, for the use of the product, from an analog video signal composed of image lines and representing the image of said article placed on a support.
When pieces of determined shape have to be cut from a leaf-like article whose outer shape is variable and which may comprise holes, for example when cigar wrappers are cut out from a tobacco leaf, every effort must be made to obtain an optimum use of the product, and processes for automatic calculation have been developed to this end.
The basic information that the computer must receive is the outer contour of the product and the holes that it may comprise, insofar as these holes are of such dimensions that they must be taken into account to determine the optimum cut-out pattern.
However, the analog video signal cannot be processed by the computer and it must firstly be converted into a digital signal, according to the known process which consists in comparing the video signal, for each image dot, with a determined threshold, and in coding the dot "1" or "0" according to whether the intensity of the signal is greater than or less than the threshold. The threshold will be suitably chosen so that the signal is coded "1" (or "0") for the support and "0" (or "1") for the article.
However, the digital signal thus obtained represents an extremely large amount of information, and the processing of such a signal necessitates memories of very large capacity and, more generally, very heavy equipment, if it is desired that the duration of the processing is compatible with practical requirements. A considerable compression of this signal is therefore indispensable.
In addition, the holes are to be taken into consideration only from a certain dimension, corresponding to a number n.sub.1 of image dots, which implies that the corresponding criterion is applied to the signal. A specific processing is necessary to this end.
In short, the problem raised consists in transmitting to the computer information in digital form containing all the necessary data, while being of minimum volume.